DDR1 SDRAM – the first memory in the DDR family has a synchronous interface, active on both edges of the clock signal. A DDR1 interface enables data transfer rates up to 400 MHz clock rate and 3200 MB/s transfer rate via a 64-bit bus.
DDR2 SDRAM – the second generation of DDR memory operates with reduced supply voltage and power consumption. The lower voltage allows the maximum clock rate to be increased to 800 MHz, leading to transfer rates up to 6400 MB/s (with a 64-bit interface).
DDR3 SDRAM – The third generation of DDR offers lower power consumption and high capacity which makes it suitable for a wide range of industrial applications. Thanks to the use of a “fly-by” bus, DDR3 may run with a clock rate of up to 1866 MHz clock rate and 15000 MB/s transfer rate.
DDR4 SDRAM – currently it’s the most commonly used DRAM type. It features a POD12 (Pseudo Open Drain 1,2 V) interface, CRC (Cyclic Redundancy Check) on the data bus, parity control on the address bus, and a DBI (Data Bus Inversion) function. The new features of the DDR4 interface enable memory clock rates above 3200 MHz, making it an ideal solution for high-performance industrial systems. DDR4 enables transfer rates up to 25600 MB/s.
DDR5 SDRAM – the latest generation of memory in the DDR family with a maximum transfer speed of 6400 MHz. Thanks to dropping the voltage from 1,2 V to 1,1 V, the power consumption has been reduced by as much as 15% overall. A further major structural change is the incorporation of power management IC (PMIC) on the module itself. This modification makes it possible to reduce redundant power management circuitry on the motherboard and allows for better power allocation, enhancing signal integrity. An additional technology applied in DDR5 modules is the ODECC (on-die error-correction code), which makes it possible to correct some errors thus increasing the reliability of the module. Finally, the new DDR5 standard comes with two sets of 32-bit channels (40-bit in case of ECC modules) – this sets them apart from modules of the previous generation. Such a solution doubles the bandwidth, which increases the speed and efficiency in accessing the memory.